Ventricular fibrillation and atrial fibrillation are common and dangerous medical conditions that cause the electrical activity of the human heart to become unsynchronized. Loss of synchronization may impair the natural ability of the heart to contract and pump blood throughout the body. Medical personnel treat fibrillation by using a defibrillator system to apply a relatively large electrical charge to the heart. If successful, the charge overcomes the unsynchronized electrical activity and gives the natural pacing function of the heart an opportunity to recapture and reestablish a normal sinus rhythm.
Defibrillator systems are medical instruments that may have multiple components, including, for example, a defibrillator to apply an electrical shock to the heart of a patient, and an electrocardiogram (ECG) monitor to evaluate the condition of the patient. More particularly, the monitor records and analyzes an ECG signal from the patient, while the defibrillator produces a high-energy defibrillation pulse to terminate ventricular or atrial fibrillation.
One or more of these components may incorporate several modules. The defibrillator, for example, may include modules for obtaining information from the patient, interacting with the operator of the defibrillator, and delivering therapy to the patient. This modular approach facilitates customization of the defibrillator to the needs of the particular application. For example, a user interface module may be selected based on the level of experience of the expected operator of the defibrillator.
The defibrillator modules typically communicate with each other using a serial data connection. In some conventional defibrillators, inter-module communication occurs over an RS-232 connection. Other conventional defibrillators use various types of serial data connections, including, for example, I2C, Microwire, or SPI connections. These types of connections have a number of disadvantages. For example, the bandwidth realized by these connections may be too low for certain applications. In addition, these connections lack extensibility. That is, flexibility in allocating functionality among various modules is limited.